Cardiac failure caused by myocardial iron overload is the most common cause of death in patients with thalassemia. Myocardial T2* mapping is widely used to detect and quantify myocardial iron in these patients. The conventional myocardial T2* mapping approach uses an ECG-triggered segmented black-blood multi-echo gradient echo (mGRE) sequence. As with any segmented k-space acquisition, data are acquired over multiple heart beats (e.g., 10 heart beats) and a patient breath-hold is required to avoid respiratory motion artifacts. However, this strategy fails in severely ill patients and others unable to breath-hold.